1. Field of the Invention
This invention is generally related to electronic cameras and more specifically to focusing mechanisms in electronic handheld cameras configured with intraoral imaging optics.
2. Description of Related Art
Electronic handheld cameras configured with intraoral imaging optics ("intraoral cameras") are used for capturing images of the inside of a patient's mouth. The camera typically has an elongated body that contains an image sensor and optics. The optics and the sensor are designed for capturing images of the inside of the mouth when the distal end of the camera is inserted into the patient's mouth. Wires carrying electronic signals typically connect the image sensor to the proximal end of the camera where a communication interface is provided to an image processing system or monitor that allows manipulation and display of the images.
Several types of focus mechanisms for the intraoral camera have been developed. One type has a rotatable dial located at approximately half-way between the proximal and distal ends. Focusing is accomplished by rotating the dial which translates into linear motion of a focusing lens with respect to a stationary image sensor. The focusing lens is positioned between the image sensor and optical elements near the distal end. Locating the dial in the middle of the camera, however, places the user's hand too close to the patient's mouth when focusing.
An alternative technique for an intraoral camera places the focus dial farther away from the distal end, at the proximal end of the camera. In that case, rotation of the dial moves the image sensor relative to the optics to achieve focus. Although in that case the dial is conveniently located far from the distal end of the camera which is inserted into the patient's mouth, long term use by repeated focusing might result in the failure of the wire connection between the image sensor and the proximal end of the camera.
Therefore, a novel intraoral camera is needed which permits a more reliable electrical connection to the image sensor while at the same time allowing the user to focus with her hand away from the patient's mouth and preferably at the rear of the camera.